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Ruppert Musical Instruments
DUAL BAND COMPRESSOR
User Manual
Ruppert Musical Instruments • 20a, rue de Bascharage • L - 4995 Schouweiler • Luxembourg
Tel./Fax: 00 352 691 379050 • Web: www.rmi.lu • E-Mail: [email protected]
Congratulations!
With the Basswitch Dual Band Compressor you have purchased a high quality piece
of musical equipment that allows effective and melodious compression of your bass
sound.
When developing the Basswitch Dual Band Compressor we focused on the needs and
wishes of the professional musician who is not willing to compromise on either sound
or the technical quality of the equipment.
The Basswitch Dual Band Compressor is manufactured, assembled and tested in
Germany to the highest quality standards using only the best brand components
available to ensure optimal treatment of the electrical signal from your instrument.
The Basswitch Dual Band Compressor offers a highly flexible but easy to handle compressor in pedal size, which is suitable for live performances as well as for studio
recordings. Inside the small, robust housing of the Basswitch Dual Band Compressor
are two high end compressors, which enable a huge variety of compression settings
but never produce pumping or distorted sounds.
Due to its specific design for bass, various parameters could be linked and automatized, resulting in a better overview, and a simple and intuitive operation. The
method used for the Basswitch Dual Band Compressor involves the continual and
automatic adaption of parameters (control variables) like attack and release times
to the bass-signal.
On the Basswitch Dual Band Compressor you will not find controls for “attack”, “decay” or “release”, but instead GAIN, COMP and VOLUME. The frequency bands that are
supposed to be processed are assigned to appropriate the compressor via the FREQ
pot. For the user this means: instead of operating 11 up to 13 controls, you will only
have four parameters to set, while keeping the widest range of options to compress
your bass sound. Particularly live on stage this simplification is of great help and
increases the fun of playing from the first moment on.
Please take the time to read this manual carefully before operating your Basswitch
Dual Band Compressor.
I wish you every success with your RMI Basswitch Dual Band Compressor. Yours,
Jacques Ruppert
Index
Introduction3
Description4
Examples of possible setups 5
Tech Talk
6
Compressor Curve Chart
7
Technical data
7
2
Introduction
via the transition frequency (FREQ), whilst COMP and GAIN control the processing of the signal.
This dual band flexibility allows in no time to adjust catchy settings, be it
for fast staccato passages or for slapping the bass.
Why a specific compressor for bass?
Audio compressors cut down the peaks or spikes, the loudest parts in a
sound pattern, thus reduce the dynamic range and make, depending on
the setting, either the amplitude envelope (i.e. the volume changes over
time) of the instrument appear more balanced or the tone sound more
punchy.
To enable reasonable settings, most audio compressors allow adjusting
attack, release, threshold and ratio for each frequency band individually.
Apart from this, you can sometimes select between hard knee and soft knee
characteristics. Even for a single band compressor this means a collection
of controls of at least 5 to 6 knobs, for dual band compressors it goes up
to 13 controls.
The design of this very sophisticated compressor setup allows users in
spite of the complexity of the bass signal, to adjust only with a few moves a
differentiated compression, without pumping or distorting the tone.
We could facilitate the control options - and therefore the amount of control
knobs on the device - by dynamically coupling attack and release to the
input signal of the bass. The soft knee characteristics we choose cause a
soft, very subtle transition from the uncompressed to the compressed tone.
In addition, for the Basswitch Dual Band Compressor we decided to use
two high end compressors which process the selected frequency bands
separately. The user selects the operating range of the two compressors
Functions and applications overview
Additional Features
• Lehle “True Sound Technology“ (for details please consult the chapter “Tech
Talk“).
• Adjustable bypass modes: in True Bypass mode gold plated contacts ensure zero losses; in Buffered Bypass mode the Basswitch Dual Band Compressor operates as a totally neutral line-driver.
• The higher voltage supply (18V) provides the Basswitch Dual Band Compressor with a wider dynamic range and thus allows adequate processing of
signals from both active and passive basses. A switcher to toggle between
variable signal strengths is not necessary.
• Specially designed to protect the controls from damage and to prevent inadvertent changes to the settings.
• The design of the housing permits easy installation: the ultra-flat base and
removable rubber feet allow the unit to be securely attached to the pedal
board using Velcro or similar.
Setting up the compressor
Setting the bypass mode
1. Turn the FREQ control fully to the left
2. Use the GAIN (top right) to select the point where you want the compressor to start working. At low settings the two compressors work on
peak levels only. If the GAIN is set higher, the compressors will be active sooner and for longer periods.
3. With the COMP pot (bottom left) you can now adjust the compression rate (“ratio“ -> that is the degree to which the compressor is
reducing dynamic range). Low compression rates produce a rather
punchy sound; if on the other hand the COMP control is set to max
(11 o’clock), the Basswitch Dual Band Compressor will act similar
to a limiter.
4. Via FREQ you can now set the point where the two frequency bands
are split and assign them to the two compressors. That is how you
can compress the low frequencies (bass) without cutting the trebles,
the tone becomes more airy, while keeping the punch in the bass
range.
5. Finally adjust the volume via VOL (Volume) to produce an equal
loudness, whether or not the compressor is switched on.
6. Simply try the great variety of different settings until you find
YOUR very sound!
In OFF status, the Basswitch Dual Band Compressor provides two
different modes of operation – in True-Bypass mode, the input and
output are linked with zero losses to one another via a relay with
gold-plated contacts. In Buffered-Bypass mode, on the other hand,
the device works as a totally neutral line-driver.
1. Disconnect the Basswitch Dual Band Compressor from the power
supply.
2. Keep the Footswitch / Button pressed.
3. Connect the Basswitch Dual Band Compressor to the mains supply
by plugging the power supply plug into the fitting input jack (915V, on the very left).
The LED above the button now flashes a sequence of 2 different
flashing signals:
• (flashes 1x) l True-Bypass mode.
• • (flashes 2x) l Buffered-Bypass mode.
Depending on the flashing signal that is shown at the moment you
release the button, you choose True-Bypass mode or Buffered-Bypass
mode. The selected mode will stay even when you disconnect your
Basswitch Dual Band Compressor from power supply, until you set
another operating mode as described above.
3
General description
3
9-15V
2
1
OUT
IN
7
4. GAIN Control
From 0 (bottom left, 7 o’clock) clockwise to 100 % (bottom right, 5
o’clock).
Use the GAIN to select the point where you want the compressor to start
working. At low settings the two compressors work on peak levels only. If
the GAIN is set higher, the compressors will be active sooner and for longer
periods of time. The LED signals when the compressors begin to operate.
5. COMP Control
From 0 (top right, 2 o’clock) clockwise to 100% (top left, 11 o’clock).
With the COMP pot you can adjust the compression rate (“ratio“ -> that
is the degree to which the compressor is reducing dynamic range). Low
compression rates produce a rather punchy sound; if on the other hand,
the COMP control is set to max (11 o’clock), the Basswitch Dual Band
Compressor will perform/ behave similar to a limiter.
4
VOLUME
GAIN
5
6
6. FREQ Control
Logarithmically from 250Hz (top right, 2 o’clock) to 12kHz (top left, 11
o’clock) clockwise. Adjust the crossover frequency here.
With the aid of this control you can change a full-range single band compressor to a dual band compressor with two frequency bands compressed
to different degrees. The two compressors in the Basswitch Dual Band
Compressor can each be assigned to one frequency band and those will
be compressed with different attack- and release-times by the auto-function of the compressors, depending on the input signal of the relevant
band.
DUAL BAND COMPRESSOR
9
8
Lehle TRUE SOUND TECHNOLOGY
7. VOLUME Control
From 0 (bottom left, 7 o’clock) to 100% (bottom right, 5 o‘clock).
Use this control to adjust the output volume in switched-on and (versus) switched-off state.
Use the Volume Control to produce an equal loudness, whether or not the
compressor is switched on.
1. Input socket
Connect your instrument here.
The Basswitch Dual Band Compressor is built to process signals from
both passive and active pickup systems.
8. Footswitch
Compression on/off; setting the bypass mode.
Press this switch to activate the compressor function of the Basswitch
Dual Band Compressor. It also enables you to change the bypass mode as
is described above (setting up the compressor, first paragraph).
This footswitch is used to activate the compressor function or to switch
to bypass-mode. If the compressor is on, the LED lights up blue, in bypass-mode the LED is white.
2. Output socket
Connect your amp or preamp here.
3. External power supply
Connect your external power supply here (9-15V DC min. 65mA or
7-12V AC with a standard 5.5x2.1mm connector).
For the Basswitch Dual Band Compressor an external power supply is
required.
This should provide a minimum of 9 volts and no more than 15 volts DC,
but alternatively you can also connect an AC voltage source with more
than 7 or up to 12V. The polarity is not relevant. The voltage supplied is
internally rectified, filtered, stabilized and then brought to 18V.
Note: To get the best out of your pedal setup we recommend that you use
high-quality power supplies with isolated output sections in your setup!
Warning: The Lehle power supply (item no. 7014) with the connector acc.
to DIN 45323 is not suitable.
9. Status LED
For compression on/off.
The LED turns blue when the compressor function is turned on.
4
Examples of possible setups
1. Jazz bass setup à la Jaco
Use mainly the bridge pickup of your instrument, add about 10% neck pickup to get about
90% signal from the crispy bridge pickup. In
addition, close the tone-control a bit to get a
slightly duller sound. The shown setup results
in a soft compression over the whole signal, for
more effect turn GAIN up a bit.
5. Medium Limiter Pop
For a distorted bass played with a plectrum
this medium limiter setup produces wonderfully smooth bass lines with a clean attack.
2. Slap Sound
Turn all controls on the Jazz bass to maximum.
This setup offers a medium compression for a
nice, balanced, slap sound with more contour.
For more effect, again simply raise GAIN.
6. More freshness
Played with plectrum or slapped, the bass
will be magically revived with this setup. Finger-style players may add a little COMP.
3. Fretless Compression
This is how a soft compression for fretless
bass looks. Only the lows are compressed,
while the high frequencies stay untouched.
This way the dynamics and the “singing”
of the bass are kept, nevertheless the bass
sounds more defined. This setup is especially
suitable for 5-strings, for 4-string basses a
slight adjustment of (more) GAIN is recommended to enhance the effect.
7. Florian’s Favourite
Favourite setup of RMI endorser Florian Friedrich (Sugarbabes, Julio Iglesias et al) “This
setup does magic on basses with “motherbucker” pickups (Gibson EB2; EB2D; EB1; EBO;
EB3 and the Epiphone equivalents).”
4. Soft Limiter Pino Paladino
Here is a soft limiting setup for fretless basses, that keeps the fretless sound while making
not too much effect audible. With a little more
GAIN and a chorus effect before the compressor, an 80s Pino Paladino Sound is easy to
create.
5
Tech Talk
The buffers are designed to effortlessly handle signals reaching the
megahertz range. At the output, the frequency bandwidth is limited to the
audible frequency range to prevent HF interference, disturbing the electronic circuitry. This guarantees optimal transient response by the circuitry
and is key to obtaining a sound that is transparent and, above all, cuts
through.
For switching, Lehle True Sound Technology uses exclusively gold-plated
contact relays and/or gold-plated switches. The decaying signal from a
string is so weak that contact materials with lower conductivity have a
negative impact on the sound. Ordinary footswitches use contact materials developed to switch high voltages (e.g. electrical power tools) as this is
their main field of application. This can be heard, for example, when, after
a switch has been in use for some time, a decaying tone starts to break
off abruptly. Relays and switches with gold-plated contacts do not have
this problem and even the smallest electrical signals can be transmitted
for years without being negatively affected. In addition, the relays used in
the Basswitch Dual Band Compressor have a lifetime about 100 times as
long as those used in ordinary footswitches.
In addition, the noise of the individual buffers adds up to produce audible
noise. It is a fact that every buffer produces some noise, even if it cannot
be heard when only a single buffer is used. The ideal solution is to have
a very high-quality buffer like the Basswitch Dual Band Compressor in
Buffered-Bypass mode at the beginning of the chain that brings the signal down to a very low impedance.
Together with typical Lehle electronic circuitry to reduce the switching pop
of relays, the combination of the above design features represents today’s
state-of-the-art solution for an uncompromising preservation of the signal and hence the sound and character of the instrument.
True-Bypass, Buffered-Bypass and True Sound
Today more and more effects pedals feature true bypass switching to
completely bypass the pedal in the signal routing when the pedal is
switched off. The target of this design is to ensure that the pedal does not
affect the electrical signal when it is switched off. This way the sound is
left unaltered – in theory. In practice, however, connecting several pedals
featuring a true bypass design in series does not improve the sound or
keep it unaltered at all. Long runs of cable and multiple connections lead
to a weak and lifeless sound. On large pedal boards the overall length of
the cable is enough for the capacitance of the cable to have a negative
effect on the sound. The capacitance of the cable acts as a low-pass filter
(= the low frequencies pass through the filter while the high frequencies
are filtered out). The price and quality of the cable you are using will not
change this physical phenomenon. A solution would be to use only devices
with buffered bypass design instead of true bypass. This, however, is only
a good solution if the buffer is of very high quality. If several units with
buffered bypass are connected in series it only needs one buffer to be
noisy, to cut the dynamics of the sound signal or to negatively affect the
sound in any other way for the sound of the whole effects chain to be
spoiled. As the saying goes: “a chain is only as strong as its weakest
link.” In addition, the noise of the individual buffers adds up to produce
audible noise. It is a fact that every buffer produces some noise, even if it
cannot be heard when only a single buffer is used. The ideal solution is to
have a very high-quality buffer like the Basswitch Dual Band Compressor
in Buffered-Bypass mode at the beginning of the chain that brings the
signal down to a very low impedance.
This makes the signal insensitive to the length of the cable. It is important, however, that this buffer is of the highest quality with the dynamic
range and headroom necessary to ensure that all the details of the bass
signal stay unaltered. The effects pedals in the downstream should then
ideally have true bypass so that they will not have a negative effect on the
now buffered signal, as the true bypass design does not reduce dynamics
and headroom or produce any noise.
The solution: change the bypass-mode as required. The bypass mode
option enables the Basswitch Dual Band Compressor to integrate ideally
to any setup.
By operating the device in Buffered-Bypass mode, it acts as a buffer, but
without corrupting the signal in any way. At this, the Basswitch Dual Band
Compressor serves a totally neutral line-driver, which has proved as the
ideal solution for long cables and complex effect board configurations.
True-Bypass mode is the best option for a small setup with short cable
routings and for when a treble-booster or a classical fuzz pedal is looped
in after the Basswitch Dual Band Compressor.
Working principle of the Basswitch Dual Band Compressor footswitches
Footswitches are pressed thousands of times during their long lifetimes
- sometimes sensitively but sometimes more brutally depending on the
situation and the musician’s temperament. An ordinary footswitch will
switch up to 20,000 times before wearing out mechanically or electrically,
which means that either it will stop working altogether or the signal will
start to lose transparency and dynamics.
The Basswitch Dual Band Compressor is equipped with high-quality Lehle
footswitches. Here the foot of the musician does not press an ordinary
footswitch but an actuator button that activates a pushbutton inside the
Basswitch Dual Band Compressor via a metal lever. Because the actuator
button and the internal pushbutton are not directly connected, the load
exerted by the foot is absorbed by the actuator button and the housing,
preserving the circuit board from mechanical stress. The design is as robust as possibly and the actuator button mounted in a special socket
making for easy and silent operation.
Inside the Basswitch Dual Band Compressor the impulse from the pushbutton activates special gold-plated relays via discrete logic circuitry.
This way the switching is done only via high-quality relays and thus
guaranteeing absolutely reliable and loss-free switching of very sensitive signals. The switching technology and the gold-plated relays in the
Basswitch Dual Band Compressor are designed to operate for up to two
million switching cycles!
What is Lehle True Sound Technology?
Lehle True Sound Technology is a combination of several electrical design measures with only one aim in view: to transmit the sound and the
character of the instrument without altering it. The voltage supplied to
the Basswitch Dual Band Compressor is internally rectified, filtered and
stabilized and then brought to almost 18 V. This gives enough headroom
to guarantee an open and dynamic sound in all situations without losing
any detail, even when confronted with pickup power peaks from plus 7 to
minus 7 volts.
6
Compressor Curve Chart
Technical data:
Weight:
Dimensions:
Supply Voltage:
Current Consumption:
Crossover Frequency:
THD+N:
Residual Noise:
Input Impedance:
Output Impedance:
Maximum Input Level:
Maximum Output Level:
Input Gain:
Output Gain:
Compression
Attack Time:
…Low Band:
…High Band:
Release Time:
…Low Band:
…High Band:
Threshold Range:
Compression Ratio:
Crossover Frequency:
Gain Cell:
Compression characteristics:
Compressor design:
400 g
145 × 60 × 45 mm (Length x Width x Height)
9-15 V AC/DC
max. 100 mA at 9 V DC;
max. 110 mA at 12 V DC
250 Hz to 12 kHz
< 0,5% (max. gains, frequency and
compression, -10 dBu input)
< 80 dBu, 22 Hz - 22 kHz, unweighted,
Output Gain = +6 dB
2.8 MegaOhm, 1 kHz
100 Ohm, 1 kHz
+14 dBu, < 1% THD, 100 Hz
+14 dBu, < 1% THD, 100 Hz
+/- 12 dB +/- 28 dB
signal dependent
20 ms to 40 ms
2.5 ms to 5 ms
100 ms to 200 ms
10 ms to 20 ms
-38 dBu to -8 dBu
1:1 to 10:1
250 Hz to 12 kHz
VCA
soft knee
rms, feedforward
7
Contact:
Ruppert Musical Instruments
20a, rue de Bascharage
L - 4995 Schouweiler
Luxembourg
Tel./Fax: 00 352 691 379050
Web: www.rmi.lu
E-Mail: [email protected]